It's much more likely a cookies/caching issue with your browser than a problem with the site. Do you have access to another browser? Login and check your food tracker - same issue, stuff still gone? Probably not. If not, try dumping the cookies and cache.
If you use a site for 2 months and it's perfect but it has one glitch one day and that makes you doubt whether you can carry on using the site all ... don't you think that might be over-reacting a little?
Sometimes glitches happen. Even if it's not your browser, it hasn't happened before in 2 months, and I've never heard of it happening before (never seen any other threads on it), so I think it's a little premature to be suggesting you leave the site yet. Give it a while. :)
Deb, in New Zealand